#define  _CRT_SECURE_NO_WARNINGS

int kthToLast(struct ListNode* head, int k) {
    struct ListNode* fast = head, * slow = head;
    while (k--)
    {
        fast = fast->next;
    }
    while (fast)
    {
        slow = slow->next;
        fast = fast->next;
    }
    return (slow->val);
}